java等比例压缩图片

① java 怎么把gif图按比例缩放

importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
importjava.awt.geom.*;
importjava.util.*;
finalclasscatextendsJFrame{
=newDimension(800,600);

publicStringgetTitle(){return"cat";}

(){returnSIZE;}

publicDimensiongetMinimumSize(){returnSIZE;}

publicDimensiongetMaximumSize(){returnSIZE;}

publicDimensiongetSize(){returnSIZE;}

privateCanvascanvas;
privateBrushbrush;

cat()throwsHeadlessException{
init();
attachListeners();
doLay();
setVisible(true);
}

privatevoidinit(){
brush=newCatBrush();
canvas=newCanvas(brush);
}

privatevoidattachListeners(){
addWindowListener(newWindowAdapter(){
publicvoidwindowClosing(WindowEvente){
System.exit(1);
}
});
}

privatevoiddoLay(){
Containercontainer=getContentPane();
container.add(canvas,BorderLayout.CENTER);
pack();
}

publicstaticvoidmain(String...args){
System.setProperty("swing.defaultlaf","com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
SwingUtilities.invokeLater(cat::new);
}

{
/**
*dopaintaction
*@
*/
voidpaint(Graphicsg);

/**
*Thecomponentthatthisbrushhold
*@returncomponentinstance
*/
ComponentgetOwner();

voidsetOwner(Componentowner);
}
{
privateComponentowner;
privateImageimg;
=AffineTransform.getScaleInstance(.4d,.4d);
publicCatBrush(){
img=Toolkit.getDefaultToolkit().getImage("G:\cat.jpg");
}

publicComponentgetOwner(){
returnowner;
}

publicvoidsetOwner(Componentowner){
this.owner=owner;
}

publicvoidpaint(Graphicsg){
Graphics2Dg2=(Graphics2D)g.create();
g2.drawImage(img,affineTransform,getOwner());
g2.dispose();
}

publicvoipdate(Observableo,Objectarg){
if(owner!=null)owner.repaint();
}
}
/**
*youcanvas
*/
{
privateBrushbrush;

privateCanvas(Brushbrush){
super();
this.brush=brush;
brush.setOwner(this);
}

protectedvoidpaintComponent(Graphicsg){
super.paintComponent(g);
if(brush==null)return;
brush.paint(g);
}
}
}

② java是怎么实现等比例缩小图片而不失真的啊

按照长宽的比例等比缩小，图片最好用矢量图片，不容易失真。。。

③ java将图片按比例缩小

Image srcImg = ImageIO.read(new FileInputStream(fnSrc) );//取源图
int width = 600; //假设要缩小到600点像素
int height = srcImg.getHeight(null)*600/srcImg.getWidth(null);//按比例，将高度缩减

System.out.println("Width: "+srcImg.getWidth(null));// 这几行是调试用
System.out.println("Height: "+srcImg.getHeight(null));
System.out.println("Width2: "+width);
System.out.println("Height2: "+height);

Image smallImg =srcImg.getScaledInstance(width, height, Image.SCALE_SMOOTH);//缩小

④ java如何实现把一个大图片压缩到指定大小的图片且长宽比不变

java要实现把一个大图片压缩到指定大小的图片且长宽比不变可以尝试以下操作：

⑤ java怎么实现通过鼠标滚轮对图片进行等比例缩放功能

给你个实例吧
public class Anniu extends JFrame implements MouseWheelListener {

private static final long serialVersionUID = 1L;

JLabel jl = null;
ImageIcon image = new ImageIcon("F://12.jpg");
public Anniu() {

}

public void init() {
setLayout(null);

jl = new JLabel(image);
setSize(800, 600);
jl.setBounds(300, 200, 200, 200);
add(jl);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.addMouseWheelListener(this);
setVisible(true);
}

@Override
public void mouseWheelMoved(MouseWheelEvent e) {
// TODO Auto-generated method stub
int num = e.getWheelRotation();
int x = (this.getWidth() - jl.getWidth()) / 2;
int y = (this.getHeight() - jl.getHeight()) / 2;
int width=jl.getWidth()+ 2 * num;
int height=jl.getHeight()+ 2 * num;
jl.setIcon(new ImageIcon( image.getImage().getScaledInstance(width, height, Image.SCALE_SMOOTH))); //重点1：按所给的大小来设置图片，不管图片有多大，总是全图显示，可能导致失真！你可以加一个大小限制，超过图片大小了则不再放大。
jl.setBounds(x + num, y + num, width, height);
this.repaint(); //刷新屏幕
}

⑥ Java怎么实现上传图片的等比缩放，原文件和缩放的文件都要上传到服务器

/**
*等比例缩放图片
*@paraminfile
*@paramoutfile
*@paramwidth
*@paramheight
*@paramquality
*@throwsIOException
*@throwsInterruptedException
*/
publicstaticvoidThumbnail(Stringinfile,Stringoutfile,intwidth,intheight,intquality)throwsIOException,InterruptedException{
//savethumbnailimagetoOUTFILE
//System.out.println("infile:"+infile);
BufferedImagethumbImage=null;
BufferedOutputStreamout=null;
Imageimage=null;
image=Toolkit.getDefaultToolkit().createImage(infile);
MediaTrackermediaTracker=newMediaTracker(newContainer());
mediaTracker.addImage(image,0);
mediaTracker.waitForID(0);
intthumbWidth=width;
intthumbHeight=height;
doublethumbRatio=(double)thumbWidth/(double)thumbHeight;
intimageWidth=image.getWidth(null);
intimageHeight=image.getHeight(null);
doubleimageRatio=(double)imageWidth/(double)imageHeight;
if(thumbRatio<imageRatio){
thumbHeight=(int)(thumbWidth/imageRatio);
}else{
thumbWidth=(int)(thumbHeight*imageRatio);
}
thumbImage=newBufferedImage(thumbWidth,thumbHeight,BufferedImage.TYPE_INT_RGB);
Graphics2Dgraphics2D=thumbImage.createGraphics();
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.drawImage(image,0,0,thumbWidth,thumbHeight,null);
out=newBufferedOutputStream(newFileOutputStream(outfile));
JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParamparam=encoder.getDefaultJPEGEncodeParam(thumbImage);
quality=Math.max(0,Math.min(quality,100));
param.setQuality((float)quality/100.0f,false);
encoder.setJPEGEncodeParam(param);
encoder.encode(thumbImage);
out.close();
thumbImage=null;
out=null;
image=null;
}

原文转载自：http://blog.chinaunix.net/uid-29337460-id-5035058.html

⑦ java如何实现把一个大图片压缩到指定大小的图片且长宽比不变

java要实现把一个大图片压缩到指定大小的图片且长宽比不变可以尝试以下操作：

⑧ 求助java压缩图片存储大小的方法

可以使用Draw这个类，通过改变像素来改变存储大小，实例如下：

(StringsrcFilePath,StringdescFilePath)throwsIOException{
Filefile=null;
BufferedImagesrc=null;
FileOutputStreamout=null;
ImageWriterimgWrier;
ImageWriteParamimgWriteParams;

//指定写图片的方式为jpg
imgWrier=ImageIO.getImageWritersByFormatName("jpg").next();
imgWriteParams=newjavax.imageio.plugins.jpeg.JPEGImageWriteParam(
null);
//要使用压缩，必须指定压缩方式为MODE_EXPLICIT
imgWriteParams.setCompressionMode(imgWriteParams.MODE_EXPLICIT);
//这里指定压缩的程度，参数qality是取值0~1范围内，
imgWriteParams.setCompressionQuality((float)1);
imgWriteParams.setProgressiveMode(imgWriteParams.MODE_DISABLED);
ColorModelcolorModel=ImageIO.read(newFile(srcFilePath)).getColorModel();//ColorModel.getRGBdefault();
//指定压缩时使用的色彩模式
//imgWriteParams.setDestinationType(newjavax.imageio.ImageTypeSpecifier(
//colorModel,colorModel.createCompatibleSampleModel(16,16)));
imgWriteParams.setDestinationType(newjavax.imageio.ImageTypeSpecifier(
colorModel,colorModel.createCompatibleSampleModel(16,16)));

try{
if(isBlank(srcFilePath)){
returnfalse;
}else{
file=newFile(srcFilePath);System.out.println(file.length());
src=ImageIO.read(file);
out=newFileOutputStream(descFilePath);

imgWrier.reset();
//必须先指定out值，才能调用write方法,ImageOutputStream可以通过任何
//OutputStream构造
imgWrier.setOutput(ImageIO.createImageOutputStream(out));
//调用write方法，就可以向输入流写图片
imgWrier.write(null,newIIOImage(src,null,null),
imgWriteParams);
out.flush();
out.close();
}
}catch(Exceptione){
e.printStackTrace();
returnfalse;
}
returntrue;
}
publicstaticbooleanisBlank(Stringstring){
if(string==null||string.length()==0||string.trim().equals("")){
returntrue;
}
returnfalse;
}

⑨ Java 按比例缩小图片应该怎么实现

public Image resizeImg(Image img, int newWidth, int newHeight) {
int imgW = img.getWidth();
int imgH = img.getHeight();
int[] srcPixels = new int[imgW * imgH];
int[] destPixels = new int[newWidth * newHeight];
img.getRGB(srcPixels, 0, imgW, 0, 0, imgW, imgH);
int srcX;
int srcY;
for (int y = 0; y < newHeight; ++y) {
for (int x = 0; x < newWidth; ++x) {
srcX = (x * imgW) / newWidth;
srcY = (y * imgH) / newHeight;
destPixels[x + y * newWidth] = srcPixels[srcX + srcY * imgW];
}
}
return Image.createRGBImage(destPixels, newWidth, newHeight, true);
}

⑩ java中怎么等比例压缩后,从中间取出图片.最好例子!谢谢大家

期待高手。